Magnetic tape cartridge

ABSTRACT

A magnetic tape cartridge has a single reel including a circular lower flange and a circular upper flange, a magnetic tape which is wound between the upper flange and the lower flange and a cartridge case including a lower case and an upper case. The upper flange closes a circular second opening of the upper case to form a central portion on an upper side of the cartridge case. It has become possible to provide a magnetic tape cartridge that has a reduced total thickness and is also advantageous in terms of costs. A magnetic tape cartridge can be also realized which is unlikely to be damaged even if it is subjected to careless handling.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a magnetic tape cartridge and,more particularly, to a magnetic tape cartridge in which a single reelwound with a magnetic tape is rotatably housed or accommodated within agenerally rectangular cartridge case.

[0003] 2. Description of the Related Art

[0004] Conventionally, there is known a magnetic tape cartridge of atype in which a single reel wound with a magnetic tape is rotatablyhoused in a cartridge case (hereinafter referred to as a one-reel type)as one used as a storage medium employed for an external storageapparatus such as a computer.

[0005] Functions of the above-mentioned magnetic tape cartridge of theone-reel type will be described referring to a representative example ofits configuration. FIG. 7 is a perspective view showing an externalappearance of a conventional general magnetic tape cartridge of theone-reel type. FIG. 8 is an exploded perspective view showing aschematic configuration of the conventional magnetic tape cartridgeshown in FIG. 7.

[0006] In the magnetic tape cartridge 60 shown in FIGS. 7 and 8, amagnetic tape 30 is wound around a single reel 56, which is composed ofa lower flange 24 and an upper flange 54 being bonded by ultrasonicwelding or the like, and the reel 56 rotatably housed in a cartridgecase 52 that is composed of an upper case 52 a and a lower case 12 bbeing fastened to each other by machine screws (not shown) or the like.

[0007] Here, the above-described lower flange 24 is composed of acylindrical reel hub 24 a around the circumference of which the magnetictape 30 is wound and a flange portion 24 b projecting from the lower endcircumference of this reel hub 24 a in the radial direction, which areintegrally molded with synthetic resin. A reel plate (not shown) or thelike for magnetically joining a rotary driving unit for rotationallydriving the reel 56, which is provided in a drive mechanism (hereinafterreferred to as a drive) of a recording/reproducing apparatus such as anexternal storage apparatus, is attached on the lower surface of thelower flange 24, that is, on the bottom external surface of the reel hub24 a.

[0008] The above-mentioned magnetic rotary driving unit engages with adriving gear formed around the lower surface of the reel plate tothereby rotate the reel 56. Simultaneously with this, a leader block 32or the like to be described later is drawn out to a predeterminedposition in a tape travelling path of the drive, whereby data can beread from and written in the magnetic tape 30.

[0009] When the magnetic tape cartridge 60 is not used, the leader block32 (a unit with which the drive having loaded the magnetic tapecartridge 60 introduces the magnetic tape 30 into the tape travellingpath within the apparatus) is held at an opening 44 for drawing out themagnetic tape 30, which is formed on one side wall surface of thecartridge case (hereinafter also referred to simply as a case) 52, withthe magnetic tape 30 being completely wound around the reel 56.

[0010] That is, when the magnetic tape cartridge 60 of such a one-reeltype is set in the drive of the external storage apparatus, the magnetictape 30 wound around the reel 56 is drawn out from the case 52 by thetape driving mechanism on the drive side and thus information isrecorded in a magnetic recording unit of the external storage apparatus(or information already recorded is read out in a reproducing unit).Then, after such objective processing is finished, the magnetic tape 30is rewound around the reel 56 in the magnetic tape cartridge 60 to behoused in the case 52 again.

[0011] Incidentally, a magnetic tape cartridge of such a one-reel typehas a disadvantage in that its thickness (i.e., its height in the reelaxial direction) is large. In addition, since the magnetic tapecartridge requires many components, it is not easy to reduce itsmanufacturing cost.

[0012] The former disadvantage of large thickness poses a significantproblem not only for the magnetic tape cartridge but also for the entiresystem in that it is inevitable to enlarge the driving mechanism on anexternal storage apparatus side as well, in which the magnetic tapecartridge is loaded to be used. In addition, the latter disadvantage ofthe large number of components contributes to the difficulty indecreasing the costs of components and the costs for assembling themagnetic tape cartridge 60.

[0013] These disadvantages are ultimately attributable to the fact thatthe conventional magnetic tape cartridge is configured to house a reelwound with a magnetic tape in a cartridge case or a cassette case(hereinafter referred to simply as a cartridge case) and to rotate thereel within the cartridge case, as in the cases of other well-knownmagnetic tape cartridges or magnetic tape cassettes and the like.

[0014] That is, from a conventional and ordinary point of view, a reelwound with a magnetic tape and a cartridge case that is a protectingunit and houses the reel exist for entirely different reasons (purposes)and are independent components, and these components are combined toconstruct a magnetic tape cartridge and a magnetic tape cassette.

[0015] Therefore, although these components are provided with parts thatoverlap with each other, such parts are left as they are. Moreover,conventionally, there have been made no discussions as to how theoverall construction should be designed by fundamentally reviewingfunctions of these components.

[0016] In addition, in the magnetic tape cartridge 60 of the one-reeltype having the above-mentioned construction as illustrated, theabove-mentioned opening 44, which becomes a passage for drawing out andrewinding the magnetic tape 30, is provided relatively close to thecorner of the cartridge case 56. Thus, if the magnetic tape cartridge 60is accidentally subjected to careless handling such as rough handling ordropping thereof, the opening 44 is likely to be damaged.

[0017] That is, in the conventional magnetic tape cartridge 60, sincethe above-mentioned opening 44 is provided relatively close to thecorner of the cartridge case 56 due in part to the configuration of thedrive side, the magnetic tape cartridge 60 is inevitably low inmechanical strength and rigidity due to its structure and is likely tobe damaged when it is subjected to careless handling.

SUMMARY OF THE INVENTION

[0018] The present invention has been devised in view of the above andother drawbacks, and it is a first object of the present invention toprovide a magnetic tape cartridge that can eliminate the above-mentioneddisadvantages in the prior art and reduce the number of components andcosts as well as its overall thickness while maintaining respectivefunctions of a reel and a cartridge case when constructing the magnetictape cartridge by combining the reel and the cartridge.

[0019] In addition, it is a second object of the present invention toprovide a magnetic tape cartridge that is made unlikely to be damagedeven if it is subjected to careless handling such as rough handling ordropping thereof.

[0020] In order to attain the first object described above, the firstaspect of the present invention provides a magnetic tape cartridgecomprising: a single reel including a circular lower flange in which anengaging portion for engaging a rotary shaft of a recording/reproducingapparatus is centered, and a circular upper flange which is arranged soas to be opposed to the lower flange and has an outer diameter largerthan the outer diameter of the lower flange; a magnetic tape which iswound between the upper flange and the lower flange; and a cartridgecase within which the single reel is rotatably accommodated and whichincludes a lower case into which the rotation shaft is inserted andwhich has a first opening at a position corresponding to the engagingportion of the lower flange, and an upper case which has a circularsecond opening having an inner diameter larger than the outer diameterof the lower flange but smaller than the outer diameter of the upperflange; wherein the upper flange closes the circular second opening ofthe upper case to form a central portion on an upper side of thecartridge case.

[0021] That is to say, the magnetic tape cartridge of the first aspectof the present invention comprises a generally rectangular cartridgecase in which a single reel wound with a magnetic tape is rotatablyhoused, wherein one of two flanges composing the reel constitutes acentral main portion of one side (an upper side) of the cartridge case.It is preferable that the central main portion of a side, which becomesan upper side when the magnetic tape cartridge is loaded into arecording/reproducing apparatus, is constituted by the upper flange thatis one of the two flanges composing the reel.

[0022] Preferably, the upper case comprises a circular cutout portionwhich is provided on an upper side of the upper case along the circularsecond opening and has an inner diameter larger than the outer diameterof the upper flange, and the upper flange comprises an annular steppedportion which is provided circumferentially on a lower side of the upperflange and fits in the circular cutout portion of the upper case from anupper side.

[0023] That is to say, it is preferable that a circular cutout portionlarger in size than the upper flange is formed on the upper surface ofthe cartridge case, and a stepped portion of the upper flange formed tohave a step fits in the cutout portion.

[0024] Preferably, a movement preventing unit for preventing relativemovement (pivot or rotational movement, rotation) of the upper case ofthe cartridge case and the upper flange is formed on an upper side ofthe circular cutout portion of the upper case and a lower side of thestepped portion of the upper flange abutting the upper side of thecircular cutout portion.

[0025] Preferably, the single reel is mounted in the cartridge case bymeans of its dead weight and the movement preventing unit functions alsoby means of the dead weight of the reel and a weight of the magnetictape wound around the reel.

[0026] Preferably, at least two reel engaging units are provided on anupper side of the upper case to engage the upper flange and prevent thesingle reel from being unwantedly disengaged from the cartridge case.

[0027] Preferably, the reel engaging unit includes an urging unit forurging the upper flange toward the upper case.

[0028] Preferably, engagement of the upper flange of the single reel bythe reel engaging unit is released when the magnetic tape cartridge isloaded into the recording/reproducing apparatus. The reel engaging unitmay be movable within an identical plane such that the engagement of thereel is released in case of loading the magnetic tape cartridge into therecording/reproducing apparatus such as an external storage apparatus.

[0029] Preferably, a magnetic tape drawing-out port, which becomes apassage for drawing out the magnetic tape from the cartridge case andrewinding the magnetic tape into the cartridge case, is provided on aside surface of the cartridge case at a position apart from a corner ofthe cartridge case.

[0030] In order to attain the second object described above, the secondaspect of the present invention provides a magnetic tape cartridgecomprising a generally rectangular cartridge case in which a single reelwound with a magnetic tape is rotatably housed, wherein a magnetic tapedrawing-out port, which becomes a passage for drawing out the magnetictape from the cartridge case and rewinding the magnetic tape into thecartridge case, is provided on a side surface of the cartridge case at aposition apart from a corner of the cartridge case.

[0031] In each aspect of the present invention, it is preferable thatthe magnetic tape drawing-out port is provided between a positioncorresponding to a screw hole used for assembling upper and lower casesand provided in the corner of the cartridge case, and a positioncorresponding to a reference hole provided in the vicinity of a centralportion of the cartridge case.

[0032] Preferably, a central position of the magnetic tape drawing-outport is located at a position apart from the corner of the cartridgecase by a distance equivalent to approximately one quarter of an edgelength of the side surface of the cartridge case.

[0033] It should be noted that the first and second aspects of thepresent invention described above can obtain the corresponding effectsto the combination of the above first and second aspects by applying thecombination.

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In the accompanying drawings:

[0035]FIG. 1 is a perspective view showing a schematic configuration ofan embodiment of a magnetic tape cartridge in accordance with thepresent invention;

[0036]FIG. 2 is a sectional view of the magnetic tape cartridge shown inFIG. 1 cut across a plane passing through a line II-II;

[0037]FIG. 3 is an exploded perspective view showing a schematicconfiguration of the magnetic tape cartridge shown in FIG. 1;

[0038]FIG. 4 is an explanatory diagrammatic view of schematic operationsfor illustrating a relation between the magnetic tape cartridge shown inFIG. 1 and a magnetic tape conveying mechanism of a drive of arecording/reproducing apparatus;

[0039]FIG. 5 is a perspective view showing a schematic configuration ofanother embodiment of a magnetic tape cartridge in accordance with thepresent invention;

[0040]FIG. 6 is a perspective view showing a schematic configuration ofstill another embodiment of a magnetic tape cartridge in accordance withthe present invention;

[0041]FIG. 7 is a perspective view showing an external appearance of aconventional general magnetic tape cartridge of a one-reel type; and

[0042]FIG. 8 is an exploded perspective view showing a schematicconfiguration of the magnetic tape cartridge shown in FIG. 7.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0043] A magnetic tape cartridge in accordance with the presentinvention will be described in detail based on embodiments shown in theattached drawings. FIG. 1 is a perspective external view showing aschematic configuration of an embodiment of the magnetic tape cartridgein accordance with the present invention. FIG. 2 is a sectional view ofthe magnetic tape cartridge cut across a plane passing through a lineII-II which is a center line between two reel stoppers to be describedlater. In addition, FIG. 3 is an exploded perspective view of themagnetic tape cartridge.

[0044] As shown in FIGS. 1 to 3, a magnetic tape cartridge 10 inaccordance with this embodiment is provided with a characteristic of afirst aspect of the present invention in which one of two flangescomposing a reel 16 (an upper flange 18 in the illustrated embodiment)constitutes a central main portion on the upper side of a cartridge case12 and a characteristic of a second aspect of the present invention inwhich an opening 42 for drawing out a magnetic tape 30 guided by aleader block 32 from the cartridge case 12 is formed in a position apartfrom the corner of the cartridge case 12.

[0045] That is, more specifically, the magnetic tape cartridge 10 of theillustrated embodiment is characterized by the following two points.First, a circular opening 14 is formed in an upper case 12 a on theupper side of the cartridge case 12, and thus the cartridge case 12 doesnot form a complete housing like a cartridge case 56 (see FIGS. 7 and 8)of the conventional magnetic tape cartridge 60, and further the upperflange 18 of the reel 16 closes the opening 14 of the upper case 12 a onthe upper side of the cartridge case 12 when the reel 16 is beingmounted, thereby forming the central main portion on the upper side ofthe cartridge case 12. Second, the opening 42 for drawing out themagnetic tape 30 guided by the leader block 32 from the magnetic tapecartridge 10 is formed in a position apart from the corner of thecartridge case 12, that is, a position apart therefrom by a distanceequivalent to approximately one fourth of the length of the side (edge)of the cartridge case 12.

[0046] The above-mentioned cartridge case 12 is constructed byassembling the upper case 12 a and a lower case 12 b with machine screws(not shown) or the like. In addition, reel stoppers 20 a and 20 b forelastically holding the reel 16 are provided on the upper side of theupper case 12 a so that the reel 16 is not unwantedly disengaged fromthe cartridge case 12. The reel stoppers 20 a and 20 b are able to pivotor rotate within the vertical plane and is urged or biased downward ortoward the upper case 12 a by a not-shown torsion spring.

[0047] In addition, the upper side of the upper case 12 a of theabove-mentioned cartridge case 12 has a circular cutout portion 15 whichis concentric with the circular opening 14 and which has a diameterlarger than that of the opening 14. A portion along the periphery of thecircular opening 14 in which the cutout portion 15 abuts the reel 16 isrecessed by one step thus forming an annular stepped portion 15 a. Theouter diameter of the upper flange 18 of the reel 16 is smaller than theinner diameter of the circular cutout portion 15 so that the upperflange 18 can be fitted in the annular stepped portion 15 a. In thisway, the upper surface of the upper flange 18 of the reel 6 is preventedfrom protruding from the upper surface of the upper case 12 a.

[0048] Moreover, the periphery on the lower side of the upper flange 18of the reel 16 is provided with an annular stepped portion 18 a havingcutouts (upward recesses; see FIG. 2). The above-mentioned steppedportion 15 a and the annular stepped portion 18 a abutting the portion15 a have gear teeth 15 b and 18 b that engage with each other such thatunwanted pivot or rotational movement (rotation) of the reel 16 which isfitted in the stepped portion 15 a of the cartridge case 12 and is in astand-by position can be prevented.

[0049] It should be noted that the reel 16 is mounted in the cartridgecase 12 so as to close the opening 14 of the upper case 12 a by its deadweight after having been inserted through the opening 14 into thecartridge case 12.

[0050] Further, the above-mentioned rotational movement preventingmechanism, which prevents a rotational or pivot movement of the reel 16by means of the fitting of the gear teeth 15 b and 18 b with each otherin the state in which the reel 16 has been fitted in the stepped portion15 a of the cartridge case 12, functions by means of the dead weight ofthe reel 16 and the weight of the magnetic tape 30 wound around the reel16 (dead weight of the reel 16 around which the magnetic tape 30 iswound). Thus, it is unnecessary to specifically provide a special urging(biasing) unit, pressing mechanism or the like for preventing therotational or pivot movement.

[0051] Here, it is possible to appropriately set shapes, sizes and thelike of the gear teeth 15 b and 18 b that are formed on the upper sideof the upper case 12 a of the cartridge case 12 and on the lower side ofthe upper flange 18 of the reel 16, respectively. In addition, it ispreferable to continuously form the gear teeth 15 b and 18 b on both therespective sides or surfaces. However, at least one of the gear teeth 15b and 18 b may be formed discontinuously.

[0052] The reel stoppers 20 a and 20 b in the foregoing description arepivotable or rotatable within the identical vertical plane. However, thereel stoppers may also be pivotable or rotatable within the identicalhorizontal plane. In either case and in particular in the type of pivotmovement or rotation within the horizontal plane, the reel stoppers 20 aand 20 b are preferably arranged to be retracted in accordance with theloading operation of the cartridge case 12 loaded into arecording/reproducing apparatus (drive mechanism) such as an externalstorage apparatus, in the direction in which the engagement of the reel16 is released.

[0053] Moreover, although it is not clear from FIG. 2, it is preferableto determine a dimension of each portion such that the upper side of theupper flange 18 of the reel 16 is at a slightly recessed positionrelative to a side wall upper end portions 22 a of the upper case 12 aof the cartridge case 12 in the state in which the reel 16 has beenfitted in the stepped portion 15 a of the cartridge case 12. It isneedless to say that this is for not applying direct load (pressure fromabove) onto the reel 16.

[0054] The illustrated magnetic tape cartridge 10 is configured asfollows: The upper flange 18 of the reel 16 is arranged parallel withthe lower flange 24 so that the flanges 18 and 24 can be opposed to eachother and has an outer diameter larger than that of the lower flange 24;and the circular opening 14 of the upper case 12 a of the cartridge case12 has an inner diameter smaller than the outer diameter of the upperflange 18 of the reel 16 but larger than the outer diameter of the lowerflange 24.

[0055] The central portion on the upper side of the upper flange 18 orthe central circular portion excluding the portion corresponding to theannular stepped portion 18 a in the illustrated case has preferably aportion to be cut 18 c for its moldability and quality improvement.

[0056] As described above, the lower flange 24 of the reel 16 mounted onthe central portion is provided with a cylindrical reel hub 24 a aroundthe circumference of which the magnetic tape 30 is wound; a circularflange portion 24 b that is integrally molded with the reel hub 24 a andsupports the wound magnetic tape 30; and engaging portions which engagesa rotational driving unit of a drive for rotatably driving the reel 16,for example a rotary shaft, as exemplified by a reel plate 24 c providedon the center of the bottom external surface of the reel hub 24 a formagnet type junction and a drive chucking 24 d provided outside the reelplate 24 c for engagement by another method. The rotational driving unitof the drive (rotary shaft) is inserted through a circular opening 26 inthe center of the lower case 12 b.

[0057] Since the constructions and operations of the lower flange 24 ofthe reel 16 and portions below the flange 24 are completely the same asthose of the above-described conventional magnetic tape cartridge,detailed description thereof is omitted here.

[0058] In the magnetic tape cartridge 10 in accordance with thisembodiment, which is constructed as described above, the upper case 12 aof the cartridge case 12 and the upper flange 18 of the reel 16 areformed substantially as one component. Thus, it becomes possible toreduce the thickness of the magnetic tape cartridge 10 by an amountequivalent to the thickness reduced as a result of forming them as onecomponent and, in addition, it may also contribute to saving ofcomponents and materials for forming them.

[0059] Moreover, in the magnetic tape cartridge in accordance with thisembodiment, the conventionally used opening 42 through which themagnetic tape 30 guided by the leader block 32 is inserted into or drawnout from the cartridge case 12 (magnetic tape drawing-out port) isarranged at a position apart from the corner of the cartridge case 12 bya distance equivalent to approximately one quarter of the length of theside (edge) of the cartridge case 12. Further, the leader block 32 isfitted in the opening 42 to be fixed and forms a part of the side wallof the cartridge case 12 of the magnetic tape cartridge 10.

[0060] Due to the construction as described above, even if the magnetictape cartridge 10 is dropped due to some cause and hits a floor or thelike at its corner, the above-mentioned opening 42 is not directlydamaged. As a result, reliability of the magnetic tape cartridge 10 andtherefore of data recorded in the magnetic tape 30 inside it can beimproved.

[0061] A positional relation between the magnetic tape cartridge 10 inaccordance with this embodiment and a magnetic tape conveying mechanismof a drive of the recording/reproducing apparatus will now be described.FIG. 4 is an explanatory diagrammatic view of schematic operations forillustrating a relation between the magnetic tape cartridge 10 inaccordance with this embodiment and a driving mechanism of therecording/reproducing apparatus such as an external storage apparatus.In the figure, reference symbols 10 a and 10 b denote reference holes ofthe magnetic tape cartridge 10, and reference character S denotes aposition of a magnetic tape drawing-out port (opening 42). Also, P1, P2,P3 and P4 denote magnetic tape guide pins on the drive side and Rdenotes a machine reel.

[0062] Here, the magnetic tape guide pins P1, P2, P3 and P4 on the driveside and the machine reel R are arranged according to the positionalrelation as shown in FIG. 4. If the magnetic tape cartridge 10 is set inthe drive, the leader block 32 guiding the magnetic tape 30 is drawnwhile passing through the peripheries of the magnetic tape guide pinsP1, P2, P3 and P4 along a route shown by an arrow, to be set in a leaderpin receiving portion of the machine reel R.

[0063] As is evident from FIG. 4, it is preferable that the position Sof the magnetic tape drawing-out port (opening 42) of the magnetic tapecartridge 10 is on the outer side with respect to the reference hole(here, 10 b) of the magnetic tape cartridge 10 but on the inner sidewith respect to the corner 10 p of the cartridge case 12 of the magnetictape cartridge 10.

[0064] Operations of the magnetic tape cartridge 10 in accordance withthis embodiment are as follows. That is, as described above, when it isnot used, the above-mentioned rotational movement preventing mechanismrealized by means of the fitting of the gears teeth 15 b and 18 b witheach other, functions due to the weight (dead weight) of the reel 16 andthe magnetic tape 30 wound around the reel 16 in the state in which thereel 16 has been fitted in the stepped portion 15 a of the cartridgecase 12, whereby the pivot movement or rotation of the reel 16 isprevented.

[0065] In addition, when the magnetic tape cartridge 10 in accordancewith this embodiment is loaded into an external storage apparatus, themagnetic tape 30 becomes ready for being drawn out from the tapedrawing-out port (opening 42) of the magnetic tape cartridge 10 into theexternal storage apparatus by means of the leader block 32. At the sametime, the reel 16 in the cartridge case 12 becomes ready for beingrotated via the drive chucking 24 d disposed in the central portion ofthe magnetic tape cartridge 10.

[0066] Further, prior to the above operation, the central portion of themagnetic tape cartridge 10 is pushed up by the components on the driveside of the external storage apparatus, whereby the fitting of the gearteeth 15 b and 18 b with each other between the upper case 12 a of thecartridge case 12 of the magnetic tape cartridge 10 and the upper flange18 of the reel 16 comes off and the restriction on the rotation of thereel 16 is released. As a result, it becomes possible to drive the reeland draw out the magnetic tape from the drive side.

[0067] The magnetic tape 30 is drawn out from the drive side in thisstate and necessary magnetic processing such as recording andreproduction is carried out. When this processing ends, the magnetictape 30 is wound (rewound) around the reel 16 in the cartridge case 12of the magnetic tape cartridge 10. When the rewinding is completed, themagnetic tape cartridge 10 is ejected from the external storageapparatus. Synchronously with this movement, the tape drawing-out port(opening 42) of the magnetic tape cartridge 10 is closed by means of thereader block 32 and the rotational movement preventing brake (fitting ofthe gear teeth 15 b and 18 b) of the reel 16 is activated to prevent anyfurther unwanted rotational or pivot movement of the reel 16.

[0068] The magnetic tape cartridge 10 shown in the above-mentionedembodiment employs a construction based on a new concept that iscompletely different from the conventional one. Thus, there is an effectin that it becomes possible to reduce the number of components and costswhen constructing the magnetic tape cartridge by combining the reel 16and the cartridge case 12, while maintaining respective functions of thereel 16 and the cartridge case 12.

[0069] In addition, in the magnetic tape cartridge 10 shown in theabove-mentioned embodiment, the position S of the magnetic tapedrawing-out port (opening 42) is on the outer side with respect to thereference hole (here, 10 b) of the magnetic tape cartridge 10 but on theinner side with respect to the corner 10 p of the cartridge case 12 ofthe magnetic tape cartridge 10, as shown in FIG. 4. Thus, the magnetictape cartridge 10 has a characteristic that it is unlikely to be damagedeven if it is accidentally subjected to careless handling such as roughhandling or dropping thereof.

[0070] Further, the magnetic tape cartridge in accordance with theabove-mentioned embodiment is provided with the characteristics of thefirst and the second aspects of the present invention. However, themagnetic tape cartridge in accordance with the present invention may beprovided with only the characteristic of the first aspect as shown inFIG. 5, or may be provided with only the characteristic of the secondaspect as shown in FIG. 6.

[0071] That is, like the magnetic tape cartridge 40 shown in FIG. 5, itmay have the same characteristic as that of the magnetic tape cartridge10 shown in FIG. 1 in that the circular opening 14 is formed in theupper case 12 a of the cartridge case 12 and that the upper flange 18 ofthe reel 16 closes the opening 14 to form the central main portion onthe upper side of the cartridge case 12. However, an opening 44 fordrawing out the magnetic tape 30 guided by the leader block 32 from themagnetic tape cartridge 40 may be provided at its corner as in theconventional magnetic tape cartridge 60.

[0072] In addition, like the magnetic tape cartridge 50 shown in FIG. 6,it may have the same characteristic as that of the magnetic tapecartridge 10 shown in FIG. 1 in that the opening 42 for drawing out fromthe cartridge case 52 the magnetic tape 30 guided by the leader block 32is provided in a position apart from the corner of the cartridge case52, that is, in a position apart therefrom by a distance equivalent toapproximately one quarter of the length of the side (edge) of thecartridge case 52. In addition, the magnetic tape cartridge may have,with respect to constructions other than this such as the constructionof the upper and the lower cases 52 a and 12 b of the cartridge case 52as well as the upper and the lower flanges 54 and 24 of the reel 56, thesame construction as that in the conventional magnetic tape cartridge60.

[0073] Further, it is needless to say that the above-mentionedembodiments simply show examples of the present invention, respectively,and the present invention is not limited to these embodiments. Forexample, it is possible to provide the above-mentioned braking mechanismusing the gear teeth between the upper side of the lower case 12 b ofthe cartridge case 12 and the lower flange 24 of the reel 16 in themagnetic tape cartridges 10 and 40 shown in FIGS. 1 to 5, although thiswould slightly reduce the effect of the present invention in reducingthe total thickness of the magnetic tape cartridge.

[0074] Since the opening 14 on the upper side of the cartridge case 12is large in the magnetic tape cartridges 10 and 40 shown in FIGS. 1 to5, it becomes also possible to integrally mold the entire cartridge case12 instead of separately molding the upper case 12 a and the lower case12 b and then assembling them together by machine screws or the like asin the conventional art. In this case, there is attained a practicaleffect in that the number of assembling steps for assembling a magneticcartridge case is reduced.

[0075] Moreover, in the magnetic tape cartridges 10 and 50 shown inFIGS. 1 to 4 and FIG. 6, the magnetic tape drawing-out port (opening42), which becomes a passage through which the magnetic tape 30 is drawnout from the cartridge cases 12 and 52 and rewound, is provided at aposition apart from the corners of the cartridge cases 12 and 52. Thus,there is attained an effect in that the magnetic tape cartridges areunlikely to be damaged even if they are accidentally subjected tocareless handling such as rough handling or dropping thereof.

[0076] The magnetic tape cartridge in accordance with the presentinvention has been described referring to various embodiments. It isneedless to say that the present invention is not limited to theabove-mentioned each embodiment but various improvement andmodifications may be made without departing from the sprit and the scopeof the present invention.

[0077] As described above in detail, according to the first aspect ofthe present invention, there is attained an effect that a magnetic tapecartridge can be realized with which it becomes possible to reduce thenumber of components and costs while maintaining respective functions ofa reel and a cartridge case when constructing the magnetic tapecartridge by combining the reel and the cartridge.

[0078] That is, according to the first aspect of the present invention,a circular cutout portion larger in size than an upper flange of theabove-mentioned reel is formed on the upper side of the cartridge case,and a stepped portion of the above-mentioned upper flange, which isformed to have a step, fits in this cutout portion. As a result, it hasbecome possible to form the upper side of the cartridge case and theupper flange of the reel as substantially one component. Then, due tosuch construction, it has become possible to provide a magnetic tapecartridge that has a reduced total thickness and is also advantageous interms of costs.

[0079] In addition, according to the second aspect of the presentinvention, there is attained a remarkable effect that a magnetic tapecartridge can be realized which is unlikely to be damaged even if it issubjected to careless handling.

[0080] Further, a magnetic tape cartridge constructed as havingcharacteristics of both the first and the second aspects of the presentinvention may enjoy both of the above-mentioned effects.

What is claimed is:
 1. A magnetic tape cartridge comprising: a singlereel including a circular lower flange in which an engaging portion forengaging a rotary shaft of a recording/reproducing apparatus iscentered, and a circular upper flange which is arranged so as to beopposed to the lower flange and has an outer diameter larger than theouter diameter of the lower flange; a magnetic tape which is woundbetween said upper flange and said lower flange; and a cartridge casewithin which said single reel is rotatably accommodated and whichincludes a lower case into which said rotation shaft is inserted andwhich has a first opening at a position corresponding to the engagingportion of said lower flange, and an upper case which has a circularsecond opening having an inner diameter larger than the outer diameterof said lower flange but smaller than the outer diameter of said upperflange; wherein said upper flange closes the circular second opening ofsaid upper case to form a central portion on an upper side of saidcartridge case.
 2. The magnetic tape cartridge according to claim 1,wherein said upper case comprises a circular cutout portion which isprovided on an upper side of said upper case along said circular secondopening and has an inner diameter larger than the outer diameter of saidupper flange, and wherein said upper flange comprises an annular steppedportion which is provided circumferentially on a lower side of saidupper flange and fits in the circular cutout portion of said upper casefrom an upper side.
 3. The magnetic tape cartridge according to claim 2,wherein a movement preventing unit for preventing relative movement ofsaid upper case of said cartridge case and said upper flange is formedon an upper side of said circular cutout portion of said upper case anda lower side of said stepped portion of said upper flange abutting saidupper side of said circular cutout portion.
 4. The magnetic tapecartridge according to claim 3, wherein said single reel is mounted insaid cartridge case by means of its dead weight and said movementpreventing unit functions also by means of the dead weight of said reeland a weight of said magnetic tape wound around said reel.
 5. Themagnetic tape cartridge according to claim 1, wherein at least two reelengaging units are provided on an upper side of said upper case toengage said upper flange and prevent said single reel from beingunwantedly disengaged from said cartridge case.
 6. The magnetic tapecartridge according to claim 5, wherein said reel engaging unit includesan urging unit for urging said upper flange toward said upper case. 7.The magnetic tape cartridge according to claim 5, wherein engagement ofsaid upper flange of said single reel by said reel engaging unit isreleased when the magnetic tape cartridge is loaded into saidrecording/reproducing apparatus.
 8. The magnetic tape cartridgeaccording to claim 1, wherein a magnetic tape drawing-out port, whichbecomes a passage for drawing out said magnetic tape from said cartridgecase and rewinding said magnetic tape into said cartridge case, isprovided on a side surface of said cartridge case at a position apartfrom a corner of said cartridge case.
 9. The magnetic tape cartridgeaccording to claim 8, wherein said magnetic tape drawing-out port isprovided between a position corresponding to a screw hole used forassembling upper and lower cases and provided in the corner of saidcartridge case, and a position corresponding to a reference holeprovided in the vicinity of a central portion of said cartridge case.10. The magnetic tape cartridge according to claim 8, wherein a centralposition of said magnetic tape drawing-out port is located at a positionapart from the corner of said cartridge case by a distance equivalent toapproximately one quarter of an edge length of the side surface of saidcartridge case.
 11. A magnetic tape cartridge comprising a generallyrectangular cartridge case in which a single reel wound with a magnetictape is rotatably housed, wherein a magnetic tape drawing-out port,which becomes a passage for drawing out said magnetic tape from saidcartridge case and rewinding said magnetic tape into said cartridgecase, is provided on a side surface of said cartridge case at a positionapart from a corner of said cartridge case.
 12. The magnetic tapecartridge according to claim 11, wherein said magnetic tape drawing-outport is provided between a position corresponding to a screw hole usedfor assembling upper and lower cases and provided in the corner of saidcartridge case, and a position corresponding to a reference holeprovided in the vicinity of a central portion of said cartridge case.13. The magnetic tape cartridge according to claim 11, wherein a centralposition of said magnetic tape drawing-out port is located at a positionapart from the corner of said cartridge case by a distance equivalent toapproximately one quarter of an edge length of the side surface of saidcartridge case.